A magnetic tunnel junction structure includes two magnetic thin-films separated by an ultra-thin layer of an insulator. The insulating layer is sufficiently thin, typically with a thickness of around 1 nanometer, such that electrons can tunnel through the insulating layer (also referred to as a tunnel barrier) if a bias voltage is applied across the two magnetic thin-films. The tunneling current depends upon the relative orientation of magnetizations of the two magnetic thin-films, while the orientation can be altered by an applied magnetic field.
Extensive interest exists in magnetic tunnel junction structures due to their usefulness in both industrial applications and scientific research. In particular, significant studies have been undertaken on the application of magnetic tunnel junction structures for storage (e.g., digital signal memories) and sensors (e.g., analog signal sensors).
A thermally-assisted magnetic tunnel junction structure is a type of magnetic tunnel junction structure. A thermally-assisted magnetic tunnel junction structure employs an electrically conducting but thermally-resistive thin-film (also referred to as a “thermal film”) in the structure to achieve a Curie temperature in one of the magnetic layers using a reduced electric heating current during operation.
For the purpose of achieving a Curie temperature for a magnetic layer within a device, a thermal layer in a thermally-assisted magnetic tunnel junction structure desirably has a high electric conductivity and a low thermal conductivity (e.g., with respect to transition metals). Existing thermally-assisted magnetic tunnel junction structures can use materials such as Ge—Sb—Te alloys. Integration of such materials, however, is difficult due to deleterious thermal and mechanical properties as well as the unusual ease in which such materials are etched in fabrication.
It is against this background that a need arose to develop the magnetic tunnel junction structures described herein.